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How to convert a ext3 or ext4 filesystem to Btrfs

Submitted by gram on Thu, 07/14/2011 - 06:33

Btrfs is a new copy on write filesystem for Linux aimed at implementing advanced features while focusing on fault tolerance, repair and easy administration. Initially developed by Oracle, Btrfs is licensed under the GPL.

Note that Btrfs does not yet have a fsck tool that can fix errors. While Btrfs is stable on a stable machine, it is currently possible to corrupt a filesystem irrecoverably if your machine crashes or loses power on disks that don't handle flush requests correctly. This will be fixed when the fsck tool is ready.

Features

Linux has a wealth of filesystems to choose from, but we are facing a number of challenges with scaling to the large storage subsystems that are becoming common in today's data centers. Filesystems need to scale in their ability to address and manage large storage, and also in their ability to detect, repair and tolerate errors in the data stored on disk.

The main Btrfs features available at the moment include:

Extent based file storage

2^64 byte == 16 EiB maximum file size

Space-efficient packing of small files

Space-efficient indexed directories

Dynamic inode allocation

Writable snapshots, read-only snapshots

Subvolumes (separate internal filesystem roots)

Checksums on data and metadata

Compression (gzip and LZO)

Integrated multiple device support

RAID-0, RAID-1 and RAID-10 implementations

Efficient incremental backup

Background scrub process for finding and fixing errors on files with redundant copies